There are currently numerous electrical connectors available which are mounted to a printed circuit board. As the size of the machines in which the printed circuit boards are installed decreases, the density of the connectors positioned on the board must increase. Also, as the machines become more sophisticated, the complexity of the printed circuit boards and the connectors must increase. Consequently, the configuration of the machines requires that electrical connectors with numerous terminals extending therefrom be mounted on a printed circuit board in such a manner so as to occupy a minimal area of board real estate.
In the early stages of the progression toward high density placement of the connectors, through-hole mounting technology was used. Mating portions of the terminals were placed in through-holes of the circuit board and held in place by soldering or some type of mechanical engagement of the pin with the sidewalls of the hole. As the need for high density increased, the amount of through-holes required also increased. However, as the diameter of the through holes is relatively large, only a fixed number of through-holes could be provided in a given area. Consequently, through-hole technology could not support the requirements for high density applications.
In order to provide for a higher density of connectors on the board, surface mount technology was utilized. As no through-holes were required, the conductive pads on the circuit board could be closely spaced, thereby allowing more contacts to be mounted in the same area of the board. Also, as the terminal were configured to be surface mounted to the printed circuit board, the terminals were designed to have resilient characteristics which allowed the terminals to compensate for board warpage and the like, thereby insuring for a more reliable interconnection.
It is also important to realize that as the density of the connectors increases, the length of the terminals cannot increase significantly. Particularly in high speed applications, the ideal solution is one which provides high density connectors which have the shortest path over which the signals must travel.
As the progression towards higher density continues, it has become imperative that every possible area of board real estate by utilized. Consequently, the invention described herein is directed to an electrical connector which can be mounted to the edge of a printed circuit board. This type of connector requires the use of both surface mount and through-hole mount technology. The invention also provides for increased performance of the electrical connector due to the relatively short lengths over which the signals must be carried.